Synthesis And Structural Characterization Of Substituted Salicylato Dimethyltitanocene Supramolecular Complexes

Supramolecular chemistry is one of the most actively pursued fields of research that involves the use of noncovalent intermolecular interactions to assemble molecules into stable well-defined structures. The forces used to organize and hold together supramolecular assemblies are weak intermolecular interactions, such as hydrogen bonds,Ï€-Ï€interactions, electrostatic interactions, and so on. It has been well documented that various supramolecular interactions dramatically affect the crystal structure. Therefore, it is one of the most important subjects in supramolecular chemistry and in crystal engineering that elucidation of the relationship of the interaction types with the molecular packing modes. Titanocene derivatives have attracted considerable interest in recent years, partly due to they act as catalysts in organic synthesis, anti-tumor activity drugs and even as antioxidative agents, and also for the versatile molecular structure and supramolecular architecture exhibited by these complexes. Salicylic acid derivatives occupy an important position in animate being, so it might provide necessary data and basic theories about their physiologically activity and catalysis to study on synthesis, characterization and superamolecular structure of substituted salicylato titanocene derivatives. Based on this point, four complexes were synthesized, and their single crystals were grown and studied. The main contents of this dissertation are as follows:1. Based on the reaction between bis(η⁵-methylcyclopentadienyl) dichlorotitanium [Cp'₂TiCl₂(Cp'=η⁵-C₅H₄Me)] and substituted salicylic acids in the presence of acetyl acetone, four dimethyltitanocene complexes: 5-chloro-salicylato dimethyltitanocene(1), 3,5,6-trichloro-salicylatodimethyltitanocene(2), 3,5-dinitro-salicylato dimethyltitanocene(3) and 3,5-dibrom-salicylato dimethyltitanocene(4) were synthesized in high yields. The complexes were characterized by elemental analysis, IR and ¹H NMR spectra.2. Four single crystals were grown in dichloromethane-hexane at low temperature, X-Ray analysis of complexes 1～4 shows that each of the complexes exhibits a four-coordinated, distorted tetrahedron structure. Each substituted salicylic acid acts as a bidentate ligand and coordinates with Ti^â…£via one oxygen atom of hydroxyl and one carboxy oxygen atom. Each complexes exhibits a three-dimensional network constructed through weak interactions, which are hydrogen bonds, such as C-H…πinteractions and F-tapeÏ€-Ï€stacking.3. Compared with similar titanocene complexes, there are more weak interactions in the crystal structure of these dimethyltitanocene complexes 1～4 just because of methyl group in the prensence of Cp ring. Furthermore, the different substitutions of the salicylic acids result in not only the conspicuous change of the weak interactions in these complexes but also the packing shape. All of the complexes 1, 2 and 3 are assembled to the three dimensional structure by hydrogen bonds and C-H…πinteractions, and moreover, there are Cl…Cl Van Der Waals Force in complex 1 and F-tapeÏ€-Ï€stacking in complex 2. The three dimensional structure is formed only by hydrogen bonds in complex 4.